If you use the directions from Google Maps and you're afraid of driving on highways or you're a biker, you'll definitely like the new option to avoid highways. "When you click the Avoid Highways checkbox, the route instantly updates to one that tries very hard to stay off of interstates, motorways, and other major roadways. This may give you a much longer path, but one that you may find more suitable," explains Google LatLong Blog.
For example, if you go from Redmond to Mountain View and avoid the highways, you need 8 extra hours.